Apparatus and method for manufacturing tube sections for heat exchangers



May 11, 1965 J. KARMAZIN 3,182,483

APPARATUS AND METHOD FOR MANUFACTURING TUBE SECTIONS FOR HEAT EXGHANGERS Filed Jan. 23, 1962 2 Sheets-Sheet 1 di 40e if y j /0 l in /f if May 11, 1965 J. KARMAzlN 3,182,483

APPARATUS AND METHOD EUR MANUFACTURING TUBE sEcTIoNs FOR HEAT EXCHANGERS Filed Jan. 23, 1962 2 Sheets-Sheet 2 L/O @Fmg/s'.

United States Patent O 3,182,483 APPARATUS AND METHOD FOR MANUFACTUR- ING TUBE SECTIONS FOR HEAT EXCHANGERS John Karmazin, Karmazin Products Corp., Wyandotte, Mich. Filed Jan. 23, 1962, Ser. No. 163,108 7 Claims. (Cl. 72-350) This invention relates |to heat exchangers and more particularly to .an apparatus and method for manufacturing heat exchangers of the fin and tube type wherein a stack of sup-enposed sheets having integral tapered tubular projections are arranged with the tubular projections thereof in telescopic relation to provide a plurality of conduits having heat transmitting fins connected thereto.

It is an object of the present invention to provide a progressive die apparatus through which a sheet of material lis incrementally advanced for the progressi-ve formation .of the tubular projections on the sheet without undue weakening or thinning of the material at one station as a result of the operation being conducted at the next succeeding station.

yIt is another object of the present invention to provide a die apparatus and method of the above character in which the work is held between the two work performing stations to assure that the material drawn into the tubular projection at the first of said stations will be fed from the metal adjacent to and -ahead of the said work performing station and not rfrom the material at the second of said work performing stations.

-It is another object of the present invention .to provide a die apparatus having a pair of relatively movable die members in which a pressure pad is yieldingly mounted on one of said members to engage the work in `a location between two work performing stations prior to the termination of the relative movement of said die members toward one another and to hold the work Iuntil the completion of said movement.

It is still another object of the present invention to provide a progressive die apparatus of the above character in which a greater amount of metal may be drawn at a se- .lected work station or stations to permit a reduction in the total number of stations and a consequent reduction in both initial die cost and the cost of die maintenance.

These and other objects of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is a plan View showing a sheet of material in .the process of manufacture by the apparatus and method of the present invention;

FIG. 2 is a lfragmentary View, partly in side elevation and partly in section, showing the -use olf the sheets formed by the apparatus and method of the present invention, a plurality of sheets being shown in stacked, nested relationship to form a heat exchanger;

FIG. 3 is a plan view, partly in section, of the die apparatus of the present invention;

iFlG. 4 is a sectional view of the structure illustrated in FIG, 3, taken along the line 4-4 thereof;

FIG. 5 is an enlarged view of a portion of the structure of FIG. 4; and Y FIG. 6 is an enlarged fragmentary sectional view of the Ystructure illustrated in FIG. 3, taken along the line 6-6 thereof.

Referring now to the drawings, FIGURE 1 will be seen to illustrate a sheet or strip of material 1) in the process of .manufacture yinto a heat exchanger. The sheet is of relatively thin gauge and is incremental-ly advanced through the die apparatus of the present invention, which is adapted to be mounted in a punch press. It will be seen that the sheet 210 is initially slit, as indicated at 12,

3,l82,483 Patented May 1l, 1965 rice and isthereafter successively indented or deformed to form a plurality of spaced tubular projections arranged in rows. The initial deformation, indicated at 14, is of relatively wide diameter and shallow depth, whereas the iinal deformation, indicated at 16, is of a substanti-ally smaller diameter and has a much greater depth or length. By reference to FIGS. 2 and 4, it will be seen that the intermediate operations tform -a `gradual transition between these shapes. The result is such that the portions of .the sheet remaining in the plane of the strip form iins having openings l1S defining the mouths of tapered tubular projections l2t).

The progressive indentation of the sheet 10 is effective to draw the metal of the sheet surrounding the projections into the .tubular projections during the forming operations, as indicated 4by the expansion yof the metal adjacent the slits 12 into the diamond shapes indi-cated at 122. The dra-wing of the metal of the sheet toward the tubes is :further -indicated by the configuration produced at the side edges of the strip, where curved indentations 24 are produced adjacent the tubular projections or tubes l2t). The expanded slits 22 and indentations 24 do not impair the ultimate utility of the heat exc-hanger but, rather, provide openings Kfor the Igreater circulation olf air therearound and, thus, facilitate the transfer of heat to or 'from the unit.

lFrom FIG. 2, it ywill be seen that the nested or telescopic relationship of the tu-bes 20 forms a plurality of conduits 26 which are normally adapted to be interconnected at their ends to provide a continuous path for the llow of lluid through the unit.

Referring now to FIGS. 3-6, the die mechanism forming the apparatus of the present invention will be seen to include an upper die member 23` adapted to be yfastened to the ram of a punch press. A die holder is secured to the die member 28 with a plate 32 interposed therebetween. The die holder 30 is provided with two parallel rows of openings for the reception of male die members 34a, 341), 34C, 34a', 34e, 341, 34g and 34h. The last die member 34h is a punch-out tool, whi-le the remaining ones of said male die members are forming tools. The male die members 34a, 34h, 34C, 34d, 34e, 341, and 34g are provided with projections 36 depending Ifrom the lower ends thereof.

A lower die member 38 is positioned on the punch press beneath the upper die structure and is provided with two rows of openings adapted to receive female die members 40a, 4Gb, 40C, 40d, 40e, 40f, 40g and 40h. `The female die :members 40a, 4011, 40e, 40d, 40e, 40f and 40g are formed with cavities 42 conformably shaped to and receiving the projections 36 .to cooperatively form the material of the strip 10 therebetween, ywhereby the material of the sheet will be progressively worked to Kform the tube portions 20. lIt will ,be seen that spring-biased ejectors 44 are positioned beneath the `female die members 40a, 40b, 40e, 49d, 4de, 46j and 40g -tor the purpose of ejecting the Work therefrom after each stroke of the upper die. The Ifemale die member 40hiis adapted to cooperate with the male die member 34h in removing a circular piece of material from the ends of the tubes 20 to open up the tubes.

A suitably apertured guide plate 46 is positioned on the lower die member 33 and is provided with guide openings 48 for receiving and guiding the movement of the male die members 34C, 34d, 34e, 341, 34g and 34h. The plate is supported by means of a pair of supports 50 positioned on opposite sides of the lower die member 38. At its left-hand end, the plate 46 has a pair of semicircular recesses 52 which cooperate with a pair of Semicircular recesses 54 formed in a block or pressure pad member 56 for the purpose of guiding the travel of the male die member 34h. The pressure pad 56 is suspended from the upper die holder S for vertical movement relative thereto and is also provided with guide openings 58 which receive the male `die members 34a. v The pressure pad 56 is held in assembly with the upper die member 36 by means of a pair of studs 60 extending into a pair of bores 62 kformed in the pressure pad 56. The portion of` each stud ott within its bore 62 is formed with an inclined or wedged shoulder 64, against which a locking set screw 66 is threaded so as to draw a studshoulder GS against the upper surface `of the pressure pad 56. The upper end of each stud 6i) is provided with -a head 7G seated within a separate one of a pair of bores 72 formed in the upper die member 30. Each stud head 70 is movable in, a bore 72 between the plate 32 and a shoulder 74'at the bottom of the bore 72. Thus, the pressure pad Sois free to move the distance of the movement afforded the head 70 within the bore 72.

The klower surface of the pressure pad 56' carries a depending hardened steel or carbide work engaging rib 76 having a rounded lower surface 7S adapted to contact the. sheet `1t). The pressure pad is biased in a downward direction away from the die holder 30 by a plurality of coil springs 80 which seat at their lower ends within the pressure, pado'and at their upper ends within the die holder 30. Thus, upon the descent of the upper die mechanism, the vrib 76 will contact the strip prior to the time that the male die members reach their ultimate position of descent.v `During .final descending movement of the upper die member 23 and the structure which it supports, the pressure pad 56 will have a lost motion relation- 'ship with the die holder 36 and, under the .force of. the springs 80, will apply pressure to the sheet along the line of contact to prevent deformation or drawing of the metal past the line of contact (tothe Aright of the line of contact in FIG. 4) toward the first male die member 34a. of the male die member 34a and the cooperating cavity V42 of the female die member 40a will come entirely from previously undeformed portions of the sheet 10 to the left of the pressure pad rib 76. It will, of course, be vappreciated that the sheet is advanced from the` left to the right, as viewed in FIG. 4, and that the material to the left of the male die member 34a has not previously been drawn or formed except for the formation of the slits 12. The pressure .pad 56 and its work contacting rib 76 assure that the metal at the second station formed by the male die member 34!) will not be unduly weakened or-deformed by the work forming operation accomplished at the first station by the male die member 34a.

In prior progressive die mechanisms which omitted the` work contacting rib 76, it was found that, when working with very ductile metal, such as aluminum, or when the tubular portions were arranged in closely-spaced rela-y tionship on the sheet, the substantial drawing of metal at the initial work station exemplified herein by the die members34a and 40a would weaken the tube atthe `second station (comprised herein by the die members 3411 and 4Gb), causing the tube 20 to open up at its upper end Vwith further drawing at asubsequent station. It has also been found that the insulation of the work at the second station `from the drawing of metal at the first,

station permits a greater bite of metal to be taken at the first station. This, in turn, permits a reduction in the number of succeeding die forming stations. In one case,

it was `found that a total of four successive stationscould be used .to produce satisfactory tubes which previously required eight stations to form without the use of the pressure pad and its work engaging rib.r It will be appreciated that the reduction in the number of stations in the progressive die substantially reduces the initial die cost nd the expense of die maintenance.

The projections 36 of the male die members 34a to 34g and the cavities 42 of the female die members 40a to 40g are preferably tapered, as disclosed in `my prior United States Patent No. 2,783,726. Said Hpatent-teaches The metal deformed by the projecting portion 36 enea the advantages to be obtained by the use of a uniform angle of taper. It should also be indicated that, while the apparatus illustrated herein is adaptedto form two parallel rows of tubes in a sheet, the present invention may be embodied in apparatus adapted to forma single row or any number of rows of tubes in sheets of material. It will also be appreciated that the tubular elementsmay be of various shapes or sections-such as oval or streamlined, circular shaped sections beingshown by way of illustration herein.

While it will be apparent that the preferred embodiment herein illustrated is well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification; variation and change without departing from the proper scope or fair meaning of the subjoined claims. Y

What is claimed is: l

1 "A progressive dieffor drawing tubular projections from a sheet of material includingfirst andksecond relatively movablel die members provided with a plurality of linearly spaced work stations forfdrawing the material of said sheet, each of saidV work stations ,comprising a projection on one of said die members'and means on the other of said die members defining a cavity for the reception of said projection, and 4means on one vof said die members engageable. with the sheet upon relative movement of said die members toward one another in a location disposed solely between an adjacent pair of work stations to prevent the drawing of material from the area of the sheet immediately adjacent one work station bythe operation of the other Work station while permitting the flow of material towardsaid work stations from the areas of the sheet immediately adjacent thereto. j

2. A progressive die for drawing tubularfprojections from a sheet of material incrementally advanced therethrough including first and second relatively movable die members provided with a plurality of linearly spaced work stations for drawing thel material of said sheet, each of said work stations comprising a projection on one of said die members and means on the other of said die members definingV a cavity for the receptionof said projection, and a work holding element on one of said die members engageablewith the sheet upon relative movement of said die -members toward one another in a linear path extending betweenthe first work station and the second work station to prevent the drawing of metal from the area of the sheet adjacent the second work station' by the operation of said first work station while permitting the flow of metal toward the said first work station from the area of thesheet immediately adjacent thereto. j 3. A progressive die for drawing tubular projections from a sheet of material incrementally advanced therethrough including first and second relativelyy movable die members provided with a plurality of linearly spaced work stations for drawing the material of said sheet, each of said work stations comprising a projection on one of'said diemembersV and means on the other of said die members defining a cavity for the .reception of said projection, and a work holding member mounted on one ofsaid members for movement relative thereto in the direction of relative movement of said ,die members, said work holding member being operable to engage the sheet upon relative movement of said die members toward-one another and beforecompletion of said relative movement in a linear path extending between an adjacent pair of work-holders, whereby the material of the sheet `immediately surrounding each work station of said adjacent pair ofwork stations will be free to flow toward its adjacent stations and the materiallof` the sheet adjacent-each of said work Y stations will not be drawn toward the other of said work work stations for drawing the material of said sheet, each of said work stations comprising a projection on one of said die members and means on the other of said die members defining a cavity for the reception of said projection, and a work holding member yieldingly mounted on one of said die members operable Ito engage and hold the sheet against a surface on the other of said die members in a path extending between an adjacent pair of work stations upon movement of said die members toward one another to prevent the drawing of material on one side of said location by operation of the work station on the other side of said location said work holding member being nonaengageable with the material of the sheet immediately surrounding said adjacent pair of work stations on the sides thereof other than the sides adjacent said path, whereby material of the sheet on each side of said path will be free to ow toward the adjacent ones of said pair of work stations.

5. A progressive die for drawing tubular projections from a sheet of material incrementally advanced therethrough including rst and second relatively movable die members provided with a plurality of linearly spaced work stations for drawing the material of said sheet, each of said work stations comprising a projection on one of said die members and means on the other of said die members defining a cavity for the reception of said projections, a pressure plate mounted lon one of said die members having a work contacting surface operable to engage the sheet and hold the sheet against a surface on the other of said die members in a limited area extending between an adjacent pair of work stations, and spring means biasing said pressure plate in a direction toward said other die member, said spring means being yieldable after contact of said work contacting surface with the sheet to permit continued relative movement of said die members toward one another while preventing the drawing of material on one side of said location by operation of the work station on the other side of said location said pressure plate being shaped so as not to contact the sheet in areas surrounding the major portions of said adjacent pair of work stations.

6. The structure set forth in claim 5 in which said work contacting surface is elongated in a direction transverse to the path of advancement of the sheet.

7. The method of making a heat exchanger component which includes forming a plurality of spaced tubular projections in a sheet of material by the simultaneous drawing of the material at a plurality of linearly spaced work stations and holding the material in a location between an adjacent pair of work stations without holding the material in locations completely surrounding said adjacent pair of work stations to prevent working of the material on one side of said location by operation of the work station on the other side of said location.

References Cited by the Examiner UNITED STATES PATENTS 2,389,738 11/45 Olney 113-42 3,116,542 1/64 Niekamp 153--2 FOREIGN PATENTS 266,942 6/50 Switzerland.

CHARLES W. LANHAM, Primary Examiner.

NEDWIN BERGER, Examiner. 

1. A PROGRESSIVE DIE FOR DRAWING TUBULAR PROJECTIONS FROM A SHEET OF MATERIAL INCLUDING FIRST AND SECOND RELATIVELY MOVABLE DIE MEMBERS PROVIDED WITH A PLURALITY OF LINEARLY SPACED WORK STATIONS FOR DRAWING THE MATERIAL OF SAID SHEET, EACH OF SAID WORK STATIONS COMPRISING A PROJECTION ON ONE OF SAID DIE MEMBERS AND MEANS ON THE OTHER OF SAID DIE MEMBERS DEFINING A CAVITY FOR THE RECEPTION OF SAID PROJECTION, AND MEANS ON ONE OF SAID DIE MEMBERS ENGAGEABLE WITH THE SHEET UPON RELATIVE MOVEMENT OF SAID DIE MEMBERS TOWARD ONE ANOTHER IN A LOCATION DISPOSED SOLELY BETWEEN AN ADJACENT PAIR OF WORK STATIONS TO PREVENT THE DRAWING OF MATERIAL FROM THE AREA OF HE SHEET IMMEDIATELY ADJACENT ONE WORK STATION BY THE OPERATION OF THE OTHER WORK STATION WHILE PERMITTING THE FLOW OF MATERIAL TOWARD SAID WORK STATIONS FROM THE AREAS OF THE SHEET IMMEDIATELY ADJACENT THERETO. 